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contented calf browsing hedge after TB testing summer 07
Okay, here goes. The paper which landed on Robert’s desk the week of our TB test wasn’t a recent publication…in fact it was published in 2006. It never receive the coverage it should have at the time. Strangely its arrival had nothing whatsoever to do with the farm or our impending TB test. It was forwarded to Robert because of his involvement in all things hedge (being chair of the national hedgerow Biodiversity Action Plan group, Hedglink and co-chair of the Devon Hedge Group).
Robert popped his head around my office door “You should take a look at this.”
“What?” I looked up at him
“A paper on bovine TB linked to hedges”
“Hedges?”I scratched the top of my head and twiddled the hair “What…hedges decrease, increase the incidences?” As always when another study is published on bTB my reactions are mixed…hope, doubt, excitement, negativity and a kind of destructive inevitability.
“Decrease apparently”
“Oh something went wrong around here then!” I said wryly “Us being one of the most heavily hedged landscapes in Britain with some of the worst incidences of TB.”I leant back in my chair “So how do you mean? Good thick boundaries between contiguous farms?” I went on pre-empting his explanation “I didn’t know this…but the spread of disease from cattle to cattle out in the field is apparently quite unusual. The vet said a TB infected animal has to have developed lesions in the head and lungs and to hawk violently onto an area of grass just before it’s ingested by another animal to get cross contamination. Interesting…I always thought it was a much more tenuous encounter” I stretched “So, what’s its claim then? The paper? Where was the research carried out?” adding tongue-in-cheek “The hedgeless, stockless arable wastes in the east of the country?”
“No. Here. In North Devon. And on the Hereford/Gloucestershire boarder!” He grinned “I’ll send you a link. Have a look for yourself!”
So I did.
The study covered 120 dairy farms, 60 with recently infected herds and 60 without, and looked at the influence of various factors on the incidence of bovine TB. These factors were farmland habitat, topography (landform), badger density, proximity of farms with breakdowns, stocking density and herd size.
As expected bTB incidence was found to be linked to herd size and distance to nearest infected farms. In line with some other studies but not all, incidence was not found to be closely linked to badger density. It was also not closely linked to the extent or configuration of deciduous woodlands nor to the extent of pasture (both favoured badger habitats).
What was new was that hedgerow characteristics were found to be strong predictors of breakdown incidence. Hedgerow abundance, the number of hedgerow gaps, and the number of ungrazed field boundaries were all important. For example, a ‘hedge-poor’ farm (as defined in the paper) would be expected on average to have a 1.6 times greater risk of bTB than a ‘hedge-rich’ farm. Considering just total hedgerow length, an increase of 1 km per 100 ha was associated with a decrease in the risk of breakdowns by about 12.5%: in absolute terms this equates to the annual risk of bTB changing from 9.2% to 8.1% for herds in the West of England: an annual reduction of 251 infected herds (based on 2004 figures). These figures were controlled for herd size and distance to next bTB case: it is not simply the case that farms with plenty of good hedgerows have a lower stocking density.
The authors conclude that habitat management appears important to a farm’s bTB risk. ‘Nature friendly’ management practices – the presence of ungrazed wildlife strips, and the greater availability, width and continuity of hedgerow – are all associated with reduced bTB incidence.
They could only speculate on the mechanism through which hedgerows may reduce incidence of bTB, but suggest it could be due to one of two factors. The first is that hedge-rich farms are managed differently – for example they have different crop rotations which reduce the likelihood of cattle eating contaminated grass. The second (and more likely) is that the presence of hedges reduces badger-cattle transmission because a higher proportion of contaminated grass is kept out of the reach of cattle. Badgers preferentially use hedgerows as movement corridors and for their latrines, so where cattle are excluded from these areas by either hedge growth or fences, contact with the bacteria is reduced.
Given the practical difficulties associated with badger culling, and the fact that to be effective it has to be carried out over large areas (because of the perturbation effect), the authors suggest that improving habitat features such as hedgerows and ungrazed wildlife margins might be a more cost effective strategy to reduce infection.
So there you have it. A piece of research I had no idea existed. And the one thing we have on this farm? Exceptional density of hedges…with very few gaps; in fact we have many more hedges now than were present on the 1840 Tithe Map.
Could this be (and I hardly dare think it, let alone say it) a reason why we ‘continue’ (whispered very quietly) to go clear?
...so! hedges are good for something other than browsing?
Friday 13th. Not that I’m superstitious. I just happened to be clasping onto pieces of wood, crossing my fingers (and toes) and nonchalantly chucking salt over my left shoulder.
Back in January Robert came into my office waving a piece of paper “Do you know anything about this?”
I looked up “No, don’t think so. What is it?”
“It’s a thing from Animal Health notifying us we’re to go onto six monthly TB testing because we’re contiguous.”
“Oh? Strange? We’ve been contiguous for ever.” Puzzled, I reached out for the piece of paper “I wonder why now?” I looked at the dates stipulated. “That’s a bugger – we’ll have just started calving. If that’s the case we’ll most probably throw up some inconclusives at the very least.” Inconclusive reactors are animals that develop lumps inbetween negative and positive; these animals have to be re-tested after six weeks.
A theory, not scientifically proven, is that animals who are suffering stress – such as those that are bulling, calving, carrying a burden of liver fluke or worms – are more likely to react unfavourably to the tuberculin skin test.
A shiver runs down my spine “But looking on the bright side” I say optimistically “I guess it means that we have sixty days to sell stock when it’s most wanted without doing a pre-movement test at our expense. If we go clear.”
To try and control the spread of TB you are allowed to move stock within sixty day of a test. If you want to move stock outside the sixty days of a routine TB surveillance test you have to pay yourself to have the animals tested.
I phoned the vets to arrange dates. It was decided – the 10th March for the test and the 13th to read the test.
So on Tuesday Sally, our vet, arrived to do the first round. Then we wait. We wait three sick-making days. I have to restrain myself from compulsively running my hands over the necks of the cattle. Then on Friday, Friday 13th, Sally returned to read the test. As always I feel ill. As always Olly says to me “I know we’ll go clear.” I wish I had his confidence.
It worked – all the touching of wood, throwing of salt and crossing of fingers – reprieve, reprieve, reprieve…we went clear. Not that I’m superstitious of course.
Culicoides sonorensis the bluetongue virus biting midge
I’ve been hanging onto this story to see if there were any developments. To date, there haven’t been.
Last week bluetongue serotype 1 (BTV1) was found on a farm in the North West, near Blackpool. It was detected in five imported pedigree Bazadaise dairy cattle from an area in France battling with both BTV1 and BTV8. The cows were culled along with one other animal in the same consignment.
These cows were moved perfectly legally having been vaccinated against BTV1 and BTV8 sixty days before travelling to the UK, following the current procedure set out by DEFRA. But, the cattle appear to have been infected with the BTV1 strain of the disease around the same time they were vaccinated and showed low level viremia when post-imported tested by DEFRA.
Defra said there was no evidence of the disease circulating, so no movement controls or additional restrictions had been put in place.
Chief veterinary officer Nigel Gibbens said:
“Taking into account the epidemiological evidence and the consideration of the risk represented to British livestock, I have taken the decision to cull these animals.
This incident shows how important it is for farmers to consider potential disease risks when buying stock. Buyers need to consider how best to protect their own businesses and those of their neighbours and make sure they are clear about the stock they are intending to buy.”
Too right it does!
What astounds me is the lack of compulsory testing before the animals are exported. I know if I wanted a particular breed of cattle I would think very, very carefully about purchasing my breeding stock from a country reeling from the effects of Bluetongue strains not yet present in the UK (well actually, I just wouldn’t!). If it was a matter of life and death (though for the life of me I can’t see that anything would be that important) I would insist on the animals being tested prior to they leaving their home premises and before they were anywhere near British shores.
Dr Ruth Watkins at least seems to understand the risks involved when importing animals from Bluetongue infected countries. From a conversation she had with Warmwell
“From a diagnostic and virologist point of view,” she says “when vaccinating cattle for possible export – (valuable animals that are special in some way) – blood samples should be taken and stored at the time vaccination is begun and then, three weeks after the second dose of vaccination, when it is known for sure that animals are going to be exported, a further blood sample should be taken. Both blood samples should then be tested for the presence of antibody and checked for bluetongue virus RNA1 and 8 or other serotypes.
While such tests might cost up to £100 pounds or so, the £1000s spent on pedigree animals and transport puts such a figure in perspective. A farmer gets no compensation for imported animals that are subsequently culled – but if such testing were done before animals are moved into the UK it would do much for the safety of movements and the reputation – and pockets – of both importers and exporters.”
She adds ruefully, “Most farmers don’t understand enough about testing. Rational virus diagnosis – i.e. using all the tests at your command – is not routinely practised and understood in veterinary medicine – but surely farmers would rather these tests were done.”
I most certainly would – wouldn’t you?
Yesterday evening I watched as clouds of midges danced in the golden rays of the setting sun outside the kitchen window. I tried to take a photo of them. This is the result. Fireflies? Perhaps. Fairies? Possibly. Dancing debris from a fire? Could be. But midges? No!
dancing cloud
Midges bring with them a sinister reputation. The more so since I’ve heard this disquieting news through the Farmers Weekly. Many farmers, with animals already stressed by the dire weather, believe rumours that if vaccinated against bluetongue disease they might fail to breed. FWi reports “The doubts over vaccinating were reflected at Penrith livestock market which reported that of 6000 mules through only two batches of ewes were vaccinated”.
The uptake of the vaccine has been so low in the North of England that only one in five livestock farms is protected.
A Cumbria suckled calf producer is quoted as saying “I’ve decided to leave my vaccine in the fridge until the spring. I want my cows safely in calf and a crop of calves on the ground before I start to jab.”
Chief veterinary officer Christianne Glossop reports that the uptake of vaccine in Wales has been disappointingly low. FWi quotes Alun Edwards, a Welsh farmer and Farmers Union of Wales office holder, as saying producers who resist vaccination to be “bloody idiots”.
I can only speak from my own experience.
I vaccinated in late May as soon as the vaccine was available in Devon. My bull had only been running with the cows for a couple of weeks before I vaccinated and as far as I know, to date, all cows and heifers I would expect to be are in calf. I had the most vulnerable animals PD (pregnancy diagnosed) when I was bTB testing the other week and they are 2½ -3 months in calf.
Despite the weather, and vaccination, my lambs have grown well and have killed out at a good average weight of 15-16kgs – Whiteface Dartmoor lambs give a small to medium size carcass. The tups go in with the ewes at the end of next week, so I will soon see how that goes.
I urge farmers to think really carefully about the consequences of not vaccinating. If your animals contract Bluetongue, even if they don’t die (with up to 70% mortality in sheep) they will suffer horrendous consequences. Abortion, stillbirth and neonatal mortality are increased with survivors suffering from infertility, depleted lactation and chronic weight loss. These things are a certainty. I know vaccination’s an added cost in a year that’s bleak, but the consequences, emotionally and financially, will be a hundred times worse with the disease.
For immediate up-to-date information on bluetongue and the various forms of available vaccination in the UK, and on the continent, follow this link to Warmwell.
Mr Edwards also questioned the sanity of importing livestock from infected areas following the first cases of bluetongue found in imported cattle on a Denbighshire farm.
So do I. So do I!
death dance?
Karin has very kindly sent me a link to a page from the Institute of Animal Health which has a selection of presentations given by several members of her group at an NFU meeting. You’ll see the presentations listed at the bottom on the left hand side– just click on them to view. (the above link is now working!)
She has also included three papers that you might find interesting
Bluetongue 1 Bluetongue 2 Bluetongue 3
Another link which you might also find informative is Farming on Sunday
If you have any questions about bluetongue the Institue of Animal Health have an email account iah.bluetongue@bbsrc.ac.uk. where your questions will be answered by one of the bluetongue group – the most appropriate person for the question.
Karin will be giving another talk in Cornwall at The Conference Hall, Duchy College, Rosewarne, Nr Camborne TR140AB on Thursday the 22nd May at 7.30pm. If it’s near enough to you I suggest to try to get there as her presentation really is superb.
I hope you find this useful. If there’s anything else you want to know I’ll see if I can help.
A few weeks ago Jennifer developed an oedema on her lower jaw known as ‘bottle jaw’. Bottle jaw or intermandibular oedema is due to protein loss from the bloodstream into the intestinal tract. The most likely cause of this is either Johne’s disease (pronounced “yo-knees”), a disease you really don’t want in your herd, or parasitism, most likely fluke, both of which damage the liver. However it could be the result of a heart condition in which case an oedema could subsequently appear on the chest.
As you can imagine, I was worried. Jennifer, if you remember, is the herd’s number one cow, the matriarch. She is also the cow, back in February, I photographed throughout the labour and birth of her massive calf. After calving I decided to supplement her feed with cereal to help her cope with the demands of a large calf and to make up for the lack of nutrients in last summer’s inferior forage. Despite this additional feeding she continued to look rather emaciated, though her character, disposition and appetite remained much as usual.
I consulted my vet when the oedema first appeared and we decided to wait twenty-four hours to see if any materialized on her chest which would indicate a heart condition. Thank heavens none did. The next stage was to try and find out what the cause was and if possible to treat it. I took a faecal sample which was sent to Starcross Laboratories to test for Johne’s disease and parasites. She was given a dose of flukicide in case the herd’s routine autumn drench for fluke had not been effective. I injected her with a multi-vitamin to boost the liver and a steroid to control the oedema.
Unfortunately Johne’s disease is incurable. Briefly it’s a serious wasting disease that affects a wide range of animals. It causes a thickening of the intestinal wall which blocks the normal absorption of food. The animal is hungry and eats but cannot absorb any nutrients. This results in wasting and finally death. Diarrhoea and bottle jaw are common signs of its presence in cattle. It’s very difficult to diagnose and often by the time any symptoms come to light the disease is well established in the herd and difficult to eradicate.
I waited nervously for the test results to come back. In the meantime Jennifer’s oedema continued to increase in size. I knew that sweet fresh grass would be the best medicine for her, indeed she was craving it, but unfortunately that wasn’t an option. One evening I found Olly in the cow palace scratching her back “I’ve a bad feeling about Jen, mum”. This was after doing some searches on the net which gleefully informed us that once the oedema appeared the animal had approximately two weeks to live!
“Well I don’t think she’s that ready to give up just yet” I replied “after all she has this year’s intake of maiden heifers to sort out and one of them’s her daughter little Jen” (her real name is Kate but she looks so like her mum that we nicknamed her little Jen). “I’m sure she’ll want to make sure that she’s putting her connections to good use and is groomed for future matriarchal succession.”
My vet phoned with the results – and joy of joy they were negative both for parasites and Johne’s! But, he warned this can sometimes be a false negative in the case of Johne’s and we should continue to monitor her. She has now been out to grass for almost a week and I think the oedema is lessening; she certainly looks to be carrying a little more weight. So hopefully this incident is due to a combination of age, her years of exceptional fertility, mothering and milk production…and the very poor quality of last summer’s haylage. Neither the herd nor I are ready to see the end of her reign. Long live Jen!
A quick update on the bluetongue information. Unfortunately there has been a technical hitch with converting the two Dutch power point presentations into pdfs. Andrew, who is very kindly doing this for me, is away on holiday this week, but as soon as he is back I’m sure that the problem will be resolved and we’ll be able to either upload the pdfs or give a link to them.
The good news is that I’m in contact with Karin from Pirbright who is keen to help and is willing put some information together for the blog. Though due to the warmer weather over the past week she has been extremely busy and won’t be able to do much before the weekend.
But, with a bit of luck, by next week I should have pulled together some useful sources of information that you will hopefully find helpful.
Locks Park Farm 
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